United Airlines will retire its last Boeing 747-400 in “late October” after nearly half a century with the carrier.

The Chicago-based carrier will “displace” its last 747 pilots on 30 October, it said in a crew resources update to pilots on 17 March. However, it does not set a date for the venerable jumbo jet’s final flight.

United will fly the 747 to London Heathrow, Frankfurt, Seoul Incheon and Shanghai Pudong from its San Francisco hub during its last month in service, the update says.

Scott Kirby, president of United, announced in January that the airline would retire the 747 by the fourth quarter, nearly a year earlier than planned.

“It’s a bittersweet milestone — this jumbo jet with its unmistakable silhouette once represented the state-of-the-art in air travel,” he said. “Today, there are more fuel-efficient, cost-effective and reliable widebody aircraft that provide an updated inflight experience for our customers traveling on long-haul flights.”

United is replacing its last 20 747s with 14 Boeing 777-300ERs, all of which are scheduled for delivery by the middle of 2017.

FlightGlobal schedules show the carrier operating its last 747 flight from Seoul to San Francisco on 29 October, however this could change based on aircraft availability and the 777 delivery schedule.

For example, on 15 March, United chief executive Oscar Munoz said the airline was “not happy” with possible delays to its new business class Polaris seats at supplier Zodiac Aerospace. While he did not explicitly say the seats were late, he did say United’s retrofit schedule was “dynamic” and that it was providing Zodiac with “lots of beneficial support”.

United Airlines' final Boeing 747-400 flight arrived in Honolulu at 15:00 local time on 7 November, ending the Queen of the Skies' 47-year run with the carrier.

The flight, UA747 operated by N118UA, was a throwback to the 1970s, when United launched its "friend ship" service with the widebody to Hawaii and on transcontinental routes across the USA.

"It is iconic," said Oscar Munoz, chief executive of the Chicago-based carrier, at the send-off party for the final flight in San Francisco. "It is an architectural and mechanical marvel, but I think more importantly it really did open up air travel to so many more people."

United's 747 final flight was not without a hitch. The flight departed San Francisco an hour late at 12:00 local time due to an issue with the jet's air conditioning valves.

The brief maintenance delay was fitting in a way, as the first 747 flight on Pan Am departed New York late due to engine issues on its inaugural sortie to London Heathrow in January 1970.

Captain David Smith, speaking after take off, took the delay lightly, joking that most passengers on the flight likely would not mind if he circled over the Pacific Ocean for several hours.

"As tough as it is to say goodbye to this iconic aircraft today, it's about celebration," said Howard Attarian, senior vice-president of flight operations at United, in a toast onboard. "We're celebrating the 747 and all the wonderful things she has brought to our airline."

United took delivery of its first 747 in June 1970, inaugurating the aircraft on the San Francisco-Honolulu route that July. At its peak, the airline operated 56 of the jumbo jets, before the fleet dwindled to just 20 at the beginning of 2017.

N118UA (MSN 28811) was delivered new to the airline in 1999, Flight Fleets Analyzer shows.

Fellow US carrier Delta Air Lines is scheduled to fly its last 747-400, inherited from Northwest Airlines when the two merged in 2009, from Seoul Incheon to Detroit on 17 December.

United, however, holds the crown for the longest continual 747 operations of any US passenger carrier.

The airline has replaced its 747s with the Boeing 777-300ER, with 10 of the widebody twinjet in its fleet and four more due in 2018.